Left ventricular (LV) hypertrophy is a significant independent risk factor for mortality from coronary heart disease, including sudden death. The proportion of sudden death to total death due to coronary heart disease remains high, at about 50% to 60%, despite the continuing downward trend in coronary heart disease mortality observed in the U.S. during the last decade. Prevalence of LV hypertrophy, determined by electrocardiogram in hypertensive patients (diastolic blood pressure greater than or equal to 90 mm Hg), including tall R wave and evidence of repolarization abnormality, is around 5%. The prevalence of LV hypertrophy by echocardiography is estimated at 44% to 48%. LV hypertrophy on electrocardiogram underestimates the magnitude of the problem of LV hypertrophy in hypertensive patients. Its overall sensitivity is less than 60%. The incidence of LV hypertrophy in hypertensive patients is lower when hypertension is treated successfully than when the patient is left either untreated or inadequately treated; successful treatment of hypertension causes regression of LV hypertrophy. However, hypertensive patients with LV hypertrophy have a poor prognosis despite treatment. The available evidence derived from the results of large clinical trials suggests that hypertensive patients should be treated before there is electrocardiographic evidence of LV hypertrophy.